Paradoxically, testosterone can have the opposite effect on the scalp if you’re genetically predisposed to baldness. In this case, testosterone inhibits hair growth in follicles on the head, causing scalp hairs to fall out and be replaced with short, fine, barely perceptible hairs.
Another curiosity: Testosterone seems to have no effect on eyebrow length. The reason your eyebrows become bushier or thinner over the years is not entirely clear. It could be because of different hormones or other aspects of aging, Dr. Anawalt said.
Scientists haven’t agreed on a theory for whether there is an evolutionary reason for age-related hair changes in men, said Dr. Steven Daveluy, an associate professor of dermatology at Wayne State University in Detroit. One hypothesis, he said, is that baldness or ear hair may have been seen as a sign of high testosterone and virility, making men with those characteristics appear to be viable mates. Whatever the possible benefit might have been, long nose hair doesn’t seem to be serving the same purpose these days.
Removal strategies
For many men, the sudden appearance of extraneous hairs may be inconsequential. But if you decide you want to get rid of them, you have several options.
Laser hair removal. For long-lasting results, laser hair removal can be done on sections of the body over several sessions. But it tends to work best on hair that is dark (not fair or gray) because the laser works by targeting the pigment in hair, Dr. Daveluy said. The light from the laser is absorbed as heat by the hair’s pigment, which then damages the follicle, preventing it from growing hair. The more sessions you do, the greater your chances of stopping hair growth permanently. One downside: It can be painful or uncomfortable.
Electrolysis. If you have light-colored hair, you may consider electrolysis, Dr. Daveluy said. During this procedure, a tiny needle is inserted into each hair follicle, where it emits an electrical current that destroys the follicle and stops it from growing hair. Like laser treatment, electrolysis can be painful and needs to be done over several sessions, particularly if you are hoping for permanent results. It also works on dark-colored hair.
The American Academy of Dermatology recommends looking for a board-certified dermatologist for laser hair removal and either a board-certified dermatologist or a board-certified electrologist for electrolysis. Also be aware that both treatments can cause irritation and permanent skin discoloration.
